Apparatus and method for block acknowledgement management in multi-link communication systems

ABSTRACT

Embodiments of an apparatus and method are disclosed. In an embodiment, a method of executing block acknowledgement operations in a multi-link communications system comprises transmitting a request for block acknowledgement response from a first multi-link device to a second multi-link device, wherein the request is either in quality of service (QoS) data frames of aggregated-media access control (MAC) protocol data unit (A-MPDU) or a block acknowledgement request, and receiving a block acknowledgment from the second multi-link device by the first multi-link device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of U.S. Provisional PatentApplication Ser. No. 62/957,177, filed on Jan. 4, 2020, U.S. ProvisionalPatent Application Ser. No. 62/980,173, filed on Feb. 22, 2020, and U.S.Provisional Patent Application Ser. No. 62/984,576, filed on Mar. 3,2020, which are incorporated herein by reference.

BACKGROUND

In multi-link communications, multi-link devices, e.g., access point(AP) multi-link logical devices (MLDs) or non-AP MLDs, execute blockacknowledgment operations, such as transmitting block acknowledgmentrequests and responding with block acknowledgments. These blockacknowledgment requests and block acknowledgments need to containvarious information to successfully execute the block acknowledgmentoperations. Thus, there is a need to design block acknowledgmentrequests and block acknowledgments that includes all the neededinformation to efficiently execute the block acknowledgment operations.

SUMMARY

Embodiments of an apparatus and method are disclosed. In an embodiment,a method of executing block acknowledgement operations in a multi-linkcommunications system comprises transmitting a request for blockacknowledgment response from a first multi-link device to a secondmulti-link device, wherein the request is either in quality of service(QoS) data frames of aggregated-media access control (MAC) protocol dataunit (A-MPDU) or a block acknowledgement request, and receiving a blockacknowledgment from the second multi-link device by the first multi-linkdevice.

In an embodiment, the request for block acknowledgement responseincludes sequence number bits in a starting sequence number field andadditional sequence number bits in another field of the request.

In an embodiment, the additional sequence number bits are in a fragmentnumber field of a block ack start sequence control field in the request.

In an embodiment, the block acknowledgement request includes anindication whether a recipient of the block acknowledgement requestneeds to update at least one of WinStartB and WinStartR value when ablock acknowledgement agreement with the recipient is not a protectedblock agreement.

In an embodiment, one block acknowledgement bitmap field in the blockacknowledgement is used to acknowledge QoS data frames of a trafficidentification (TID) from an A-MPDU source.

In an embodiment, a plurality of bits in a fragment number field of astarting sequence number control field of a block acknowledgementinformation field in the block acknowledgement indicates that a blockacknowledgment bitmap field is more than 256 bits and also indicatessize of the block acknowledgment bitmap field.

In an embodiment, B3 of fragment number field being equal to 1, B0 offragment number field being equal to 0 and various values of B2 and B1of fragment number field indicate the block acknowledgment bitmap fieldwith bit length of 512 or 1024.

In an embodiment, the block acknowledgement is carried in greater than20 MHz Extremely High Throughput (EHT) physical protocol data unit(PPDU).

In an embodiment, a block acknowledgement bitmap length of the blockacknowledgement is based on a difference of sequence numbers ofacknowledged frames instead of a negotiated block acknowledgement buffersize.

In an embodiment, the block acknowledgement request is carried in anA-MPDU to announce a starting sequence number of a solicited blockacknowledgement.

In an embodiment, a multi-link communications system comprises a firstmulti-link device, and a second multi-link device, wherein the firstmulti-link device is configured to transmit a request for blockacknowledgment response to the second multi-link device, wherein therequest is either in quality of service (QoS) data frames ofaggregated-media access control (MAC) protocol data unit (A-MPDU) or ablock acknowledgement request, and wherein the second multi-link deviceis configured to transmit a block acknowledgment to the secondmulti-link device.

In an embodiment, the request for block acknowledgement responseincludes sequence number bits in a starting sequence number field andadditional sequence number bits in another field of the request.

In an embodiment, the additional sequence number bits are in a fragmentnumber field of a block ack start sequence control field in the request.

In an embodiment, the request includes an indication whether a recipientof the request needs to update at least one of WinStartB and WinStartRvalue when a block acknowledgement agreement with the recipient is not aprotected block agreement.

In an embodiment, one block acknowledgement bitmap field in the blockacknowledgement is used to acknowledge QoS data frames of a trafficidentification (TID) from an A-MPDU source.

In an embodiment, a plurality of bits in a fragment number field of astarting sequence number control field of a block acknowledgementinformation field in the block acknowledgement indicates that a blockacknowledgment bitmap field is more than 256 bits and also indicatessize of the block acknowledgment bitmap field.

In an embodiment, B3 of fragment number field being equal to 1, B0 offragment number field being equal to 0 and various values of B2 and B1of fragment number field indicate the block acknowledgment bitmap fieldwith bit length of 512 or 1024.

In an embodiment, a block acknowledgement bitmap length of the blockacknowledgement is based on a difference of sequence numbers ofacknowledged frames instead of a negotiated block acknowledgement buffersize.

In an embodiment, a multi-link device of a multi-link communicationssystem comprises a processor configured to transmit a request for blockacknowledgement response to a second multi-link device of the multi-linkcommunications system, wherein the request is either in quality ofservice (QoS) data frames of aggregated-media access control (MAC)protocol data unit (A-MPDU) or a block acknowledgement request, andreceive a block acknowledgment from the second multi-link device.

In an embodiment, the request for block acknowledgement responseincludes sequence number bits in a starting sequence number field andadditional sequence number bits in another field of the request.

Other aspects in accordance with the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrated by way of example of the principlesof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a multi-link communications system in accordance with anembodiment of the invention.

FIG. 2 shows a Media Access Control (MAC) Protocol Data Unit (MPDU) thatcan be used in the multi-link communications system in accordance withan embodiment of the invention.

FIG. 3 shows an aggregated-MPDU (A-MPDU) that can be used in themulti-link communications system in accordance with an embodiment of theinvention.

FIG. 4 shows a block acknowledgment request (BAR) that can be used inthe multi-link communications system in accordance with an embodiment ofthe invention.

FIG. 5 shows a block acknowledgment (BA) that can be used in themulti-link communications system in accordance with an embodiment of theinvention.

FIG. 6 is a block diagram of an originator and a recipient, illustratingan exchange of an A-MPDU and a BA, in accordance with an embodiment ofthe invention.

FIG. 7 shows a new MPDU that includes an Additional Sequence Numberfield in accordance with an embodiment of the invention.

FIG. 8 shows a compressed BAR with a Solicited BA Bitmap Size field inaccordance with an embodiment of the invention.

FIG. 9 shows a new multi-traffic identification (TID) BAR with aSolicited BA Bitmap Size field in accordance with an embodiment of theinvention.

FIG. 10 shows a BAR with a TID field of a quality of service (QoS)Control field in a MAC header in accordance with an embodiment of theinvention.

FIG. 11 shows a Long Sequence Number field of an MPDU Delimiter of anA-MPDU subframe in accordance with an embodiment of the invention.

FIG. 12 shows an Additional Sequence Number And Bitmap Length field thatfollows a Block Ack Start Sequence Control field in a Per AID TID Infofield of a BA in accordance with an embodiment of the invention.

FIG. 13 shows an example of a BA operation in accordance with anembodiment of the invention.

FIG. 14 is a flow diagram of a method of managing block acknowledgementoperations in a multi-link communications system in accordance withembodiments of the invention.

Throughout the description, similar reference numbers may be used toidentify similar elements.

DETAILED DESCRIPTION

It will be readily understood that the components of the embodiments asgenerally described herein and illustrated in the appended figures couldbe arranged and designed in a wide variety of different configurations.Thus, the following more detailed description of various embodiments, asrepresented in the figures, is not intended to limit the scope of thepresent disclosure, but is merely representative of various embodiments.While the various aspects of the embodiments are presented in drawings,the drawings are not necessarily drawn to scale unless specificallyindicated.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by this detailed description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present invention should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present invention. Thus,discussions of the features and advantages, and similar language,throughout this specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages, and characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize, in light ofthe description herein, that the invention can be practiced without oneor more of the specific features or advantages of a particularembodiment. In other instances, additional features and advantages maybe recognized in certain embodiments that may not be present in allembodiments of the invention.

Reference throughout this specification to “one embodiment”, “anembodiment”, or similar language means that a particular feature,structure, or characteristic described in connection with the indicatedembodiment is included in at least one embodiment of the presentinvention. Thus, the phrases “in one embodiment”, “in an embodiment”,and similar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

FIG. 1 depicts a multi-link communications system 100 in accordance withan embodiment of the invention. In the embodiment depicted in FIG. 1,the multi-link communications system includes at least one AP MLD 102,and multiple non-AP MLDs 104-1, 104-2, 104-3. The multi-linkcommunications system can be used in various applications, such asindustrial applications, medical applications, computer applications,and/or consumer or appliance applications. In some embodiments, themulti-link communications system is a wireless communications system,such as a wireless communications system compatible with an Institute ofElectrical and Electronics Engineers (IEEE) 802.11 protocol. Forexample, the multi-link communications system may be a wirelesscommunications system compatible with an IEEE 802.11be protocol. In someembodiments, the multi-link communications system includes one or moreAP MLDs and/or one or more non-AP MLDs. Although the depicted multi-linkcommunications system 100 is shown in FIG. 1 with certain components anddescribed with certain functionality herein, other embodiments of themulti-link communications system 100 may include fewer or morecomponents to implement the same, less, or more functionality. Forexample, in some embodiments, the multi-link communications systemincludes multiple AP MLDs, more than three non-AP MLDs, and/or less thanthree non-AP MLDs. In yet another example, although the multi-linkcommunications system 100 is shown in FIG. 1 as being connected in acertain topology, the network topology of the multi-link communicationssystem 100 is not limited to the topology shown in FIG. 1.

In the embodiment depicted in FIG. 1, the AP MLD 102 includes multipleAPs 110-1, 110-2, 110-3, and one common entity 111. The APs implementthe features related to the specific links, e.g., medium access andframe transmission/reception. The common entity includes the featuresshared by all links (APs), e.g., non-AP MLD management, and reorderingof the received data frames before transmitting them to the up layer.The APs 110-1, 110-2, 110-3 may be implemented in hardware (e.g.,circuits), software, firmware, or a combination thereof. The APs 110-1,110-2, 110-3 may be fully or partially implemented as an integratedcircuit (IC) device. In some embodiments, the APs 110-1, 110-2, 110-3are wireless APs compatible with at least one WLAN communicationsprotocol (e.g., at least one IEEE 802.11 protocol). For example, the APs110-1, 110-2, 110-3 may be wireless APs compatible with an IEEE 802.11beprotocol. In some embodiments, an AP is a wireless AP that connects to alocal area network (e.g., a LAN) and/or to a backbone network (e.g., theInternet) through a wired connection and that wirelessly connects towireless stations (STAs), for example, through one or more WLANcommunications protocols, such as an IEEE 802.11 protocol. In someembodiments, an AP includes at least one antenna, at least onetransceiver operably connected to the at least one antenna, and at leastone controller operably connected to the corresponding transceiver. Insome embodiments, the least one transceiver includes a physical layer(PHY) device. The at least one controller operably may be configured tocontrol the at least one transceiver to process received packets throughthe at least one antenna. In some embodiments, the at least onecontroller is implemented within a processor, such as a microcontroller,a host processor, a host, a digital signal processor (DSP), or a centralprocessing unit (CPU), which can be integrated in a correspondingtransceiver. Each of the APs 110-1, 110-2, 110-3 of the AP MLD mayoperate in a different frequency band. For example, the AP 110-1 mayoperate in 2.4 gigahertz (GHz) frequency band, the AP 110-2 may operatein 5 GHz frequency band, and the AP 110-3 may operate in 6 GHz frequencyband. In the embodiment depicted in FIG. 1, the AP MLD is connected to adistribution system (DS) 106 through a distribution system medium (DSM)108. The distribution system (DS) 106 may be a wired network or awireless network that is connected to a backbone network such as theInternet. The DSM 108 may be a wired medium (e.g., Ethernet cables,telephone network cables, or fiber optic cables) or a wireless medium(e.g., infrared, broadcast radio, cellular radio, or microwaves).Although the AP MLD 102 is shown in FIG. 1 as including three APs, otherembodiments of the AP MLD 102 may include fewer than three APs or morethan three APs. In addition, although some examples of the DSM 108 aredescribed, the DSM 108 is not limited to the examples described herein.

In the embodiment depicted in FIG. 1, the non-AP MLD 104-1 includesmultiple non-AP stations (STAs) 120-1, 120-2, 120-3, and one commonentity 121. The STAs implement the features related to the specificlinks, e.g., medium access and frame transmission/reception. The commonentity includes the features shared by all links (STAs), e.g.,association state maintenance with the AP MLD 102 and reordering of thereceived data frames before transmitting them to the up layer. The STAs120-1, 120-2, 120-3 may be implemented in hardware (e.g., circuits),software, firmware, or a combination thereof. The STAs 120-1, 120-2,120-3 may be fully or partially implemented as an IC device. In someembodiments, the non-AP STAs 120-1, 120-2, 120-3 are wireless devicesthat wirelessly connect to wireless APs. For example, at least one ofthe non-AP STAs 120-1, 120-2, 120-3 may be a laptop, a desktop personalcomputer (PC), a mobile phone, or other wireless device that supports atleast one WLAN communications protocol. In some embodiments, the non-APSTAs 120-1, 120-2, 120-3 are wireless devices compatible with at leastone IEEE 802.11 protocol (e.g., an IEEE 802.11be protocol). In someembodiments, the non-AP MLD has one Media Access Control (MAC) dataservice interface. In an embodiment, a single address is associated withthe MAC data service interface and is used to communicate on the DSM108. In some embodiments, the AP MLD 102 and/or the non-AP MLDs 104-1,104-2, 104-3 identify which communications links support the multi-linkoperation during a multi-link operation setup phase and/or exchangesinformation regarding multi-link capabilities during the multi-linkoperation setup phase. Each of the non-AP STAs 120-1, 120-2, 120-3 ofthe non-AP MLD may operate in a different frequency band. For example,the non-AP STA 120-1 may operate in 2.4 GHz frequency band, the non-APSTA 120-2 may operate in 5 GHz frequency band, and the non-AP STA 120-3may operate in 6 GHz frequency band. Each of the non-AP MLDs 104-2,104-3 may be the same as or similar to the non-AP MLD 104-1. Forexample, the non-AP MLD 104-2 or 104-3 includes multiple non-AP STAs. Insome embodiments, each STA includes at least one antenna, at least onetransceiver operably connected to the at least one antenna, and at leastone controller connected to the corresponding transceiver. In someembodiments, the at least one transceiver includes a PHY device. The atleast one controller operably may be configured to control the at leastone transceiver to process received packets through the at least oneantenna. In some embodiments, the at least one controller is implementedwithin a processor, such as a microcontroller, a host processor, a host,a DSP, or a CPU, which can be integrated in a corresponding transceiver.

In the embodiment depicted in FIG. 1, the non-AP MLD 104-1, 104-2, or104-3 communicates with the AP MLD 102 through multiple communicationslinks 112-1, 112-2, 112-3. For example, each of the non-AP STAs 120-1,120-2, 120-3 communicates with an AP 110-1, 110-2, or 110-3 through acorresponding communications link 112-1, 112-2, or 112-3. Although thenon-AP MLD 104-1 is shown in FIG. 1 as including three non-AP STAs,other embodiments of the non-AP MLD 104-1 may include fewer than threenon-AP STAs or more than three non-AP STAs. In addition, although the APMLD 102 communicates (e.g., wirelessly communicates) with the non-APMLDs 104-1, 104-2, 104-3 through multiple links 112-1, 112-2, 112-3, inother embodiments, the AP MLD 102 may communicate (e.g., wirelesslycommunicates) with the non-AP MLDs through more than threecommunications links or less three than communications links.

Turning now to FIG. 2, a MAC Protocol Data Unit (MPDU) 200, which is awireless frame, that can be used in the multi-link communications system100 in accordance with an embodiment of the invention is shown. The MPDUis a quality of service (QoS) data frame. As shown in FIG. 2, the MPDU200 includes a MAC header 202, a frame body 204 and a frame checksequence (FCS) 206. In the illustrated embodiment, the MAC header 202includes a Frame Control field 208, a Duration Identification (ID) 210,an Address 1 field 212, an Address 2 field 214, an Address 3 field 216,a Sequence Control field 218, an Address 4 field 220, a Quality ofService (QoS) Control field 222, and an HT control 224. The SequenceControl field 218 includes a Fragment Number field 226 and a SequenceNumber field 228.

MPDUs, such as the MPDU 200, may be aggregated and transmitted as anaggregated-MPDU (A-MPDU) 300, which is shown in FIG. 3. The A-MPDU 300in accordance with an embodiment of the invention includes an A-MPDUpre-End-of-Frame (pre-EOF) padding 302 and an EOF Padding 304. TheA-MPDU pre-EOF padding 302 includes a number of A-MPDU subframes 306. Asshown in FIG. 3, each A-MPDU subframe 306 includes an MPDU delimiter308, an MPDU 310 and padding 312.

For block acknowledgment operations, block acknowledgement requests(BARs) and block acknowledgements (BAs), which are MPDU control frames,are exchanged. A BAR 400 that can be used in the multi-linkcommunications system 100 in accordance with an embodiment of theinvention is shown in FIG. 4. As depicted in FIG. 4, the BAR 400includes a Frame Control field 402, a Duration field 404, a ReceiverAddress (RA) field 406, a Transmitter Address (TA) field 408, a BARControl field 410, a BAR Information field 412 and an FCS 414. The BARControl field 410 includes a BAR Ack Policy field 416, a Multi-TrafficIdentification (TID) field 418, a Compressed Bitmap field 420, aGroupcast with Retries (GCR) field 422, a Reserved field 424, and a TIDInformation field 426. If the BAR 400 is a multi-TID BAR, the BARInformation field 412 includes a Per TID Information field 428 and aBlock Ack Starting Sequence Control field 430, which is repeated foreach TID. The Block Ack Starting Sequence Control field 430 includes aFragment Number field 432 and a Starting Sequence Number field 434.

A BA 500 that can be used in the multi-link communications system 100 inaccordance with an embodiment of the invention is shown in FIG. 5. TheBA may be solicited by a BAR or an A-MPDU as a request for blockacknowledgement response. As depicted in FIG. 5, the BA 500 includes aFrame Control field 502, a Duration field 504, a Receiver Address (RA)field 506, a Transmitter Address (TA) field 508, a BA Control field 510,a BA Information field 512 and an FCS 514. The BA Control field 510includes a BA Ack Policy field 516, a Multi-TID field 518, a CompressedBitmap field 520, a GCR field 522, a Reserved field 524, and a TIDInformation field 526. If the BA 500 is a compressed BA, the BARInformation field 512 includes a Block Ack Starting Sequence Controlfield 528 and a Block Ack Bitmap field 530. If the BA 500 is a multi-STABA, the BAR Information field 512 includes a Per AID TID Informationfield 532, which is repeated for each <AID, TID> tuple. The Per AID TIDInformation field 532 includes an AID TID Information field 534, a BlockAck Starting Sequence Control field 536 and a Block Ack Bitmap field538.

Turning now to FIG. 6, a block diagram of an originator 602, e.g., theAP MLD 102, and a recipient 604, e.g., the non-AP MLD 104-2,illustrating an exchange of an A-MPDU and a BA, in accordance with anembodiment of the invention is shown. The originator 602 includes atransmit buffer control 606 and an aggregation control 608, which arefunctional components of the originator. The transmit buffer control 606operates to define the size of a transmit buffer per RA/TID asWinStart_(o) and WinSize_(o) to receive multiple MPDUs. The aggregationcontrol 608 operates to aggregate the multiple MPDUs to form an A-MPDU,which is transmitted to the recipient 604. The recipient 604 includes adisaggregation control 610, a scoreboard context control 612, and areceive reorder buffer control 614, which are functional components ofthe recipient. The disaggregation control 610 operates to deaggregatethe received A-MPDU to separate the A-MPDU subframes to retrieve theMPDUs. The scoreboard context control operates to define the buffer sizeas WinStart_(R) and WinSize_(R) to keep track of MPDUs that have beenproperly received and to create a BA, which is transmitted back to theoriginator 602. The BA includes at least a bitmap and a start sequencenumber, which is the sequence number of the oldest data frame from theoriginator 602. The receive reordering buffer control 614 operates todefine the size of a reordering buffer per RA/TID as WinStartB andWinSize_(B) to recorder the received MPDUs in a proper order to send tothe upper layer.

BAR for Larger BA Buffer Sizes

In some embodiments, BAR needs to be changed or modified for larger BAbuffer sizes. BAR change is not required when the negotiated BA buffersize is no more than 1024. In some embodiments, BAR needs to be changedor modified for larger BA buffer sizes. BAR change is not required whenthe negotiated BA buffer size is no more than 1024. In some embodiments,BAR change may not be required when the negotiated BA buffer size ismore than 1024 and no more than 2048. However, BAR change may berequired when the negotiated BA buffer size is more than 1024 and nomore than 2048 if greater than 4096 sequence number space is required.BAR change is required when the negotiated BA buffer size is more than2048 because greater than 4096 sequence number space requires additionalsequence number bits.

In one embodiment, some bits in the Fragment Number subfield of a BlockAck Start Sequence Control field can be used to carry the additionalsequence number bits. This method can be used for compressed BARs andmulti-TID BARs. This method may be applied in Extremely High Throughput(EHT) MPDUs and in frames from an EHT AP/STA to another EHT STA/AP usingthe Fragment Number subfield of the Sequence Control in the MAC headerof the frame.

In another embodiment, for compressed BARs, some reserved bits in theBAR Control field can be used to carry the additional sequence numberbits for the compressed BARs. In this embodiment, for multi-TID BARs,some reserved bits in the Per TID Info field can be used to carry theadditional sequence number bits in the multi-TID BARs.

In still another embodiment, some reserved bits in the BAR Control fieldcan be used to carry the additional sequence number bits.

In still another embodiment, a new optional field “Additional SequenceNumber” is added in the MAC header to carry the additional sequencenumber bits, as illustrated in FIG. 7. As shown in FIG. 7, a new MPDU700 in accordance with this embodiment includes an Additional SequenceNumber field 702, in addition to other common MPDU fields, which weredescribed above with respect to the MPDU 200. The length of the newAdditional Sequence Number field 702 may be 1 octet.

BAR for Larger BA Buffer Size and No WinStart_(B/R) Update Indication

For a block acknowledgement (ack) agreement that is not a protectedblock agreement, a BAR may need to indicate whether the recipient of theBAR needs to update the WinStart_(B)/WinStart_(R) under multi-linkoperation. This can avoid the discarding of retransmitted frame inreceive reordering buffer or the discarding of reception record in thescoreboard context control if the following happen: (1) the initialframe retransmission and the frame retransmission are in differentlinks, (2) the BAR requests partial acknowledgement information oftransmit buffer control when the single transmit buffer control isapplied to multiple links, and (3) the BA agreement is a block ackagreement that is not a protected block agreement.

For a block ack agreement that is not a protected block agreement andthat has larger BA buffer size (e.g., greater than 2048), bothadditional sequence number bits and no WinStartB/WinStartR Updateindication are needed. In an embodiment, some bits in the FragmentNumber subfield of the Block Ack Start Sequence Control field can beused to indicate the additional sequence number bits and to indicate noWinStart_(B)/WinStart_(R) update. This solution can be used incompressed BARs and multi-TID BARs. In another embodiment, some reservedbits in the BAR Control field can be used to indicate the additionalsequence number bits and no WinStart_(B)/WinStart_(R) update incompressed BARs, and some reserved bits in the Per TID Info field can beused to indicate the additional sequence number bits and noWinStart_(B)/WinStart_(R) update in multi-TID BARs. In still anotherembodiment, some reserved bits in the BAR Control field can be used toindicate the additional sequence number bits and noWinStart_(B)/WinStart_(R) update.

BAR Update to Indicate BA Bitmap Size

In some embodiments, as illustrated in FIG. 8, a new compressed BARvariant is defined where a new “Solicited BA Bitmap Size” field 806 isadded to a BAR information field 800 in accordance with an embodiment ofthe invention. Thus, the BAR information field 800 of this newcompressed BAR variant includes a Fragment Number field 802, a StartingSequence Number field 804 and the new Solicited BA Bitmap Size field806. The Solicited BA Bitmap Size field 806 carries the solicited BAbitmap size information. In a particular implementation, a value carriedin the Solicited BA Bitmap Size field indicates the solicited BA bitmapsize with the following mapping: “0” indicates a BA bitmap size of 32;“1” indicates a BA bitmap size of 64; “2” indicates a BA bitmap size of128; “3” indicates a BA bitmap size of 256; “4” indicates a BA bitmapsize of 512; and so on. In an embodiment, the recipient can respond witha smaller BA bitmap size if fewer frames are acknowledged. This newcompressed BAR variant can be applied to multi-user (MU)-BARs.

In some embodiments, as illustrated in FIG. 9, a new multi-TID BARvariant is defined where a new “Solicited BA Bitmap Size” field 906 isadded to a BAR information field 900 in accordance with an embodiment ofthe invention. Thus, the BAR information field 900 of this new multi-TIDBAR variant includes a Per TID Info field 902, a Block Ack StartingSequence Control field 904 and the new Solicited BA Bitmap Size field906. The Solicited BA Bitmap Size field 906 carries the solicited BAbitmap size. In a particular implementation, a value carried in theSolicited BA Bitmap Size field indicates the solicited BA bitmap sizewith the following mapping: “0” indicates a BA bitmap size of 32; “1”indicates a BA bitmap size of 64; “2” indicates a BA bitmap size of 128;“3” indicates a BA bitmap size of 256; “4” indicates a BA bitmap size of512; and so on. In an embodiment, the recipient can respond with asmaller BA bitmap size if fewer frames are acknowledged. This newmulti-TID BAR variant can be applied to MU-BARs.

Explicit Indication

In an A-MPDU where the A-MPDU transmitter wants smaller BA bitmap size,the updated (multi-TID or compressed) BAR is aggregated. In anembodiment, the ack policy of the QoS Data frame is set to 00 (ImplicitBlock Ack Request). If aggregated BAR is missing, the BA bitmap sizedefined by the negotiated BA buffer size is used. In another embodiment,the ack policy of the QoS Data frame is set to 11 (Block Ack). Ifaggregated BAR is missing, the recipient of the A-MPDU will not respondwith a BA.

If the updated BAR is a multi-TID BAR, then the updated multi-TID BAR isin a multi-TID A-MPDU. If the updated BAR is a compressed BAR, then theupdated compressed BAR is in a single-TID A-MPDU. A variant to this isthat a multi-TID BAR with one pair of Per TID Info and Block AckStarting Sequence Control is used in a single-TID A-MPDU, which providesthe space for including the additional sequence number bits.

In some embodiments, using an updated MU-BAR, an AP may indicate whetherthe AP wants smaller BA bitmap size for each TID from each solicitedSTA.

HE (High Efficiency) Control to Indicate BA Bitmap Size

In some embodiments, the HE Control field may be used to indicate the BAbitmap size. In these embodiments, the Starting Sequence Control fieldand the Solicited BA Bitmap Size field are added to the HE Controlfield. In order to support multi-TID A-MPDUs, the TID should also beadded to the HE Control field. A variant to this is that the TID in theQoS Data frames is used. In an embodiment, the HE Control fields in theQoS Data frames of different TIDs are different.

Indication of Additional Sequence Number

In some embodiments, each STA/AP announces whether it supports greaterthan 12-bit sequence number through a management frame in EHTCapabilities element, Extended Capabilities element or other elements.In some embodiments, all EHT STAs/APs may support greater than 12-bitsequence number, and there would be no need for any announcement.

In an embodiment, one bit in the TID field of the QoS Control field inthe MAC header of a frame, such as a BAR, indicates whether theadditional sequence number is carried in the frame. As an example, FIG.10 shows the BAR 200 with a TID field 1030 of the QoS Control field 222in the MAC header 202 in accordance with an embodiment of the invention.In this example, the QoS Control field 222 includes the TID field 1030,a Long Sequence Number field 1032, a “EOSP/Queue Size Indication/TXOPDuration Indication” field 1034 and a TXOP Limit/Queue Size/TXOPduration field 1036. If the TID field 1030 indicates that the additionalsequence number is carried in the frame, the additional sequence numberis carried in the Fragment Number field 226 of the Sequence Controlfield 218 of the MAC header 202. In this embodiment, the transmitopportunity (TXOP) holder that supports greater than 12-bit sequencenumber transmits the frames by using greater than 12-bit sequence numberif the recipient of the frames supports greater than 12-bit sequencenumber.

In another embodiment, one bit in the MPDU Delimiter of a A-MPDUsubframe, e.g., redefining the reserved B1 as Long Sequence Numberfield, indicates whether the additional sequence number carried in theMPDU that follows MPDU Delimiter are the additional sequence numberbits. As an example, FIG. 11 shows a Long Sequence Number field 1140 ofthe MPDU Delimiter 308 of an A-MPDU subframe 306, which also includesthe MPDU 310 and the Padding 312, in accordance with an embodiment ofthe invention. In this example, the MPDU 310 is a BAR, such as the BAR200. Thus, the MPDU 310 includes all the components of the BAR 200. Asshown in FIG. 11, the MPDU Delimiter 308 includes an EOF field 1140, theLong Sequence Number field 1142, an MPDU Length field 1144, a cyclicredundancy check (CRC) field 1146 and a Delimiter Signature field 1148.If the MPDU Delimiter 308 indicates that the additional sequence numberis carried in the subframe 306, the additional sequence number iscarried in the Fragment Number field 226 of the Sequence Control field218 in the MAC header 202 of the MPDU 310 in the A-MPDU subframe 306.Again, in this embodiment, the TXOP holder that supports greater than12-bit sequence number transmits the frames by using greater than 12-bitsequence number if the recipient of the frames supports greater than12-bit sequence number.

BA for Larger BA Buffer Size

In some embodiments, different techniques may be applied to acknowledgeQoS data frames. In an embodiment, one Block Ack Bitmap field in acompressed BA or in a multi-STA BA can be used to acknowledge QoS dataframes of a TID from an A-MPDU source. In another embodiment, multipleBlock Ack Bitmap fields in a compressed BA or in a multi-STA BA can beused to acknowledge QoS data frames of a TID from an A-MPDU source. Inboth embodiments, the additional lengths of Block Ack Bitmap field maybe 512 bits, 1024 bits, 2048 bits and 4096 bits.

In some embodiments, the length of the Block Ack Bitmap field of a BAmay be indicated using different techniques. In an embodiment, severalbits in the Fragment Number field of the Starting Sequence NumberControl field can be used to indicate that the Block Ack Bitmap field ismore than 256 bits. For example, the third bit (B3) being 1 in theFragment Number field may indicate that the Block Ack Bitmap field isgreater than 256 bits and additional one or two bits in the FragmentNumber field may further indicate one of the various lengths.

In some embodiments, the following table can be used to indicate a512-bit BA Bitmap size and a 1024-bit BA Bitmap size using the FragmentNumber field in Compressed Block Ack, Multi-STA Block Ack: 512-bit BAbitmap is indicated by the B3 of Fragment Number field equal to 1, B2and B1 of Fragment Number field equal to 0, B0 of Fragment Number fieldequal to 0; 1024-bit BA bitmap is indicated by the B3 of Fragment Numberfield equal to 1, B2 and B1 of Fragment Number field equal to 1, B0 ofFragment Number field equal to 0.

Block Ack Fragment Bitmap Number subfield Fragmentation subfield Maximumnumber of B2- Level 3 length MSDUs/A-MSDUs that B3 B1 B0 (ON/OFF)(octets) can be acknowledged 0 0 0 OFF  8 64 0 1 0 Reserved Reserved 0 20 32 256  0 3 0 Reserved Reserved 0 0 1 ON  8 16 0 1 1 Reserved Reserved0 2 1 32 64 0 3 1 Reserved Reserved 1 0 0 OFF 64 512  1 1 0 128  1024  12 0 Reserved Reserved and 3 1 Any 1 Reserved Reserved NOTE- A CompressedBlockAck frame with B0 of the Fragment Number subfield set to 1 is notsent to an HE STA whose Dynamic Fragmentation Support subfield in the HECapabilities element it transmits is not set to 3. NOTE- A Multi-STABlockAck frame with B0 of the Fragment Number subfield set to 1 cannotbe sent to an HE STA unless the HE Capabilities element received fromthe HE STA has the Dynamic Fragmentation Support subfield equal to 3.

In another embodiment, the reserved bits in the BA Control field can beused to indicate that the Block Ack Bitmap field is more than 256 bits.In some implementation, this approach may be used only in CompressedBAs.

In some embodiments, the presence of additional number bits (e.g., withgreater than 4096 sequence number space) may be indicated usingdifferent techniques. In an embodiment, one or more bits (e.g., twobits) in the Fragment Number field of the Starting Sequence NumberControl field can be used to indicate the additional sequence numberbits. Additional two bits with the current Sequence Number field have16384 sequence number space.

In another embodiment, the reserved bits in the BA Control field can beused to indicate that the Block Ack Bitmap field carries the additionalsequence number bits. In some implementation, this approach may be usedonly in compressed BAs.

In still another embodiment, the B3 bit in the Fragment Number field canbe used to indicate that an Additional Sequence Number And Bitmap Lengthfield, which can indicate 1 octet, 2 octets or other length, follows theBlock Ack Start Sequence Control field in the Per AID TID Info field ofthe BA. In an embodiment, the Additional Sequence Number And BitmapLength field includes an Additional Sequence Number subfield (e.g., a2-bit subfield) and an additional Bitmap Length subfield (e.g., a 2-bitsubfield). When the B3 bit and the B0 bit in the Fragment Number fieldhave a value of 1, the Additional Bitmap Length subfield can indicatethe Block Ack Bitmap fields with length of 64 octets, 128 octets orother length. FIG. 12 illustrates an Additional Sequence Number AndBitmap Length field 1204 that follows a Block Ack Start Sequence Controlfield 1202 in a Per AID TID Info field 1200 of a BA in accordance withan embodiment of the invention.

In still another embodiment, the Additional Sequence Number field is nottransmitted in the BA frames. In this embodiment, the Start SequenceNumber field indicates the 12-bit LSB of the start sequence number ofthe acknowledged QoS Data frames. The Fragment Number field indicatesthe BA bitmap size. The value in the Additional Sequence Number field ofthe frame with the smallest sequence number identified by a BA bitmap issame as the additional sequence number bits in the solicited BAR orA-MPDU. When BAR is not allowed to be aggregated with QoS Data frames inan A-MPDU, the QoS Data frames in an A-MPDU can solicit BA if all theQoS Data frames have the same value in their Additional Sequence Numberfields. As an alternative, in the HE Control field, the smallest valueof the Additional Sequence Number field of a TID of QoS Data frame iscarried.

An example of a BA operation in accordance with this embodiment isillustrated in FIG. 13. Let's assume that in the soliciting BAR, theAdditional Sequence Number field (2 bits) has values of “11”. The BAStart Sequence Number for the TID has value 0x3FF6.

In some embodiments, when the maximal Block Ack Bitmap field is no morethan VALUE1 (e.g., 1024), the block ack for QoS Data frames of a TIDgreater than VALUE1 from an A-MPDU source can be carried in multipleBlock Ack Bitmap fields, which can be in a multi-STA BA or can be in anenhanced compressed BA where multiple Block Ack Bitmap fields are in theBA Information field.

In some embodiments, when a multi-STA BA is addressed to STAs that donot support Block Ack Bitmap field greater than 256 bits and to STAsthat support Block Ack Bitmap field greater than 256-bit, the Bitmapfield greater than 256 bits will not be carried in the multi-STA BA. Inan alternative embodiment, the Per AID TID Info fields with Block AckBitmap fields greater than 256 bits are carried after the Per AID TIDInfo fields with Block Ack Bitmap fields less than or equal to 256 bits.

Methods to Decrease BA Size and/or Transmission Time

In some embodiments, instead of transmitting a BA in a non-HT duplicatedphysical protocol data unit (PPDU), the BA is carried in a very HighThroughput (VHT)/High Efficiency (HE)/Extremely High Throughput (EHT)PPDU greater than 20 MHz. When a HE/EHT PPDU is used and there is nobasic service set (BSS) color collision, the TXOP field in the PHYheader carries the remaining TXOP duration with granularity of 8 us/256us, as defined in IEEE 802.11ax. In order to be fair to legacy neighborSTAs in 2.4/5 GHz band, Contention-Free End Beacon (CF-End) in not-HTduplicated PPDU may be transmitted at the end of the TXOP to avoid EIFSrecovery.

In some embodiments, the BA bitmap length selection is based on thedifference of sequence numbers of the acknowledged frames instead of thenegotiated BA buffer size. For example, when the negotiated BA buffersize is 1024 and the difference of sequence numbers of acknowledgedframes is less than 64, a single 64-bit Block Ack Bitmap field is used.The Block Ack Bitmap field can have length Value1 (e.g., 64) if thefollowing conditions are true: (1) the negotiated BA size is more thanValue1 and no more than Value2 (e.g., the negotiated BA size is 1024 asValue2 and Value1 is 64) where Value1 and Value2 are the allowed BAbitmap sizes in one Block Ack Bitmap field, (2) the difference betweenthe largest sequence number and the smallest sequence number of theacknowledged frames is less than Value1 (the sequence number differenceof the received QoS Data frames of the TID is less than 64), and (3) asingle Block Ack Bitmap is used for a TID.

In some embodiments, a BAR is carried in an A-MPDU to announce thestarting sequence number of the solicited BA. The HE Control in an MPDUmay announce the Starting Sequence Number of the solicited BA.

In some embodiments, the smallest sequence number in an A-MPDU thatsolicits BA is the starting sequence number of the solicited BA. Forunprotected BA agreement, the BAR carries the indication about whetherthe starting sequence number of the scoreboard context buffer and thereorder buffer is adjusted or not per the BAR frame. This can avoidframe discarding in reordering buffer and acknowledgement informationdiscarding in scoreboard context buffer.

In some embodiments, multiple Block Ack Bitmap fields (or multiple PerAID TID Info fields) with same length or different length for a TID froman A-MPDU source are used to decrease the BA size. For example, when thenegotiated BA buffer size is 768, one 512-bit Block Ack Bitmap field andone 256-bit Block Ack Bitmap field can be used to decrease the BAlength. As another example, when the negotiated BA buffer size is 768,three 256-bit Block Ack Bitmap fields can be used to decrease the BAlength.

In some embodiments, partial all l's acknowledgement can be used todecrease the multi-STA BA size. In these embodiments, a QoS frame isacknowledged by the multi-STA BA frame if the following conditions aretrue: (1) three Per AID TID Info fields whose AID11 and TID are samerespectively are continuously placed in a BA; (2) the Ack Type of thefirst Per AID TID Info field and the Ack Type of the third Per AID TIDInfo field are 0 (which indicates with BA Bitmap); (3) the Ack Type ofthe second Per AID TID Info field is 1 (which indicates without BABitmap and Block Ack Starting Sequence Control); (4) the sequence numberof the frame is no less than the sum of the value in the StartingSequence Number field of the first Per AID TID Info field and the lengthof Block Ack Bitmap in bits; and (5) the sequence number of the frame isless than the value in the Starting Sequence Number field of the thirdPer AID TID Info field. For example, in this embodiment, if MPDU framesfrom 0 to 256 and from 800 to 1024 are partially received and MPDUframes from 257 to 799 are all correctly received, then a BA Bitmap forthe MPDU frames from 257 to 799 are not transmitted in the multi-STA BAframe. For the MPDU frames from 0 to 256, an AID TID Info field, a BlockAck Starting Sequence Control field and a Block Ack Bitmap field aretransmitted in the multi-STA BA frame. Similarly, for the MPDU framesfrom 800 to 1024, another AID TID Info field, another Block Ack StartingSequence Control field and another Block Ack Bitmap field aretransmitted in the multi-STA BA frame. However, for the MPDU frames from257 to 799, only an AID TID Info field is transmitted in the multi-STABA frame.

In some embodiments, a partial all 0's acknowledgement can be used todecrease the BA size. In one embodiment, a QoS frame is not acknowledgedby the multi-STA BA frame if the following conditions are true: (1) twoPer AID TID Info fields whose AID11 and TID are same respectively arecontinuously placed in a multi-STA BA; (2) the Ack Type of the first PerAID TID Info field and The Ack Type of the second Per AID TID Info fieldare 0 (with BA Bitmap); (3) the sequence number of the frame is no lessthan the sum of the value in the Starting Sequence Number field of thefirst Per AID TID Info field and the length of Block Ack Bitmap in bits;and (4) the sequence number of the frame is less than the value in theStarting Sequence Number field of the second Per AID TID Info field. Forexample, in this embodiment, if MPDU frames from 0 to 256 and from 800to 1024 are partially received and MPDU frames from 257 to 799 are allcorrectly received, then the MPDU frames from 257 to 799 are notacknowledged in the multi-STA BA frame. For the MPDU frames from 0 to256, an AID TID Info field, a Block Ack Starting Sequence Control fieldand a Block Ack Bitmap field are transmitted in the multi-STA BA frame.Similarly, for the MPDU frames from 800 to 1024, another AID TID Infofield, another Block Ack Starting Sequence Control field and anotherBlock Ack Bitmap field are transmitted in the multi-STA BA frame.However, for the MPDU frames from 257 to 799, no information istransmitted in the multi-STA BA frame.

In another embodiment, a QoS frame is not acknowledged by the CompressedBA frame if the following conditions are true: (1) two combinations orsets of the Block Ack Starting Sequence Control field plus the Block AckBitmap field are continuously placed in a multi-STA BA, (2) the sequencenumber of the frame is no less than the sum of the value in the StartingSequence Number field of the first Block Ack Starting Sequence Controlfield and the length of the first Block Ack Bitmap in bits; and (3) andthe sequence number of the frame is less than the value in the StartingSequence Number field of the second Block Ack Starting Sequence Controlfield. For example, in this embodiment, if MPDU frames from 0 to 256 andfrom 800 to 1024 are partially received and MPDU frames from 257 to 799are all correctly received, then the MPDU frames from 257 to 799 are notacknowledged in the Compressed BA frame. For the MPDU frames from 0 to256, a Block Ack Starting Sequence Control field and a Block Ack Bitmapfield are transmitted in the Compressed BA frame. Similarly, for theMPDU frames from 800 to 1024, another Block Ack Starting SequenceControl field and another Block Ack Bitmap field are transmitted in theCompressed BA frame. However, for the MPDU frames from 257 to 799, noinformation is transmitted in the Compressed BA frame.

BSS Operating Parameter Announcement

In some embodiments, for greater than 80 MHz bandwidth (BW), the channelsegment center frequency 0 and the channel segment center frequency 1decide whether one or two channel segments exist in the BSS. When BSS BWis greater than or equal to 160/80+80 MHz, the BW in the HE/VHToperating channel, the channel segment center frequency 0, the channelsegment center frequency 1 are used. The channel segment centerfrequency 0 and the channel segment center frequency 1 are used forgreater than 160/80+80 MHz BW.

In some embodiments, static channel puncture is announced through a 20MHz available channel bitmap. In an embodiment, for 240 MHz BWannouncement, 240 MHz BSS is a 320 MHz BSS with 80 MHz channel beingpunctured. In another embodiment, 240 MHz is announced by the BW field.

In some embodiments, the announced BSS operating BW for HE STA is nomore than the maximal BW of the subchannel that includes primary 20 MHzchannel and does not include any punctured 20 MHz channel A variant tothis is that the channel width in operating mode notification is no morethat the maximal BW of the subchannel that includes primary 20 MHzchannel and does not include any punctured 20 MHz channel.

In some embodiments, for a BW less than or equal to 60 MHz/80 MHz+80MHz, the EHT MCS and NSS are no less than the HE MCS, NSS respectively.

A method of managing block acknowledgement operations in a multi-linkcommunications system in accordance with embodiments of the invention isnow described with reference to a flow diagram of FIG. 14. At step 1402,a request for block acknowledgement response is transmitted from a firstmulti-link device to a second multi-link device, wherein the request iseither in quality of service (QoS) data frames of aggregated-mediaaccess control (MAC) protocol data unit (A-MPDU) or a blockacknowledgement request. At step 1404, a block acknowledgment from thesecond multi-link device is received by the first multi-link device.

Although the operations of the method(s) herein are shown and describedin a particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operations may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be implemented in anintermittent and/or alternating manner.

It should also be noted that at least some of the operations for themethods described herein may be implemented using software instructionsstored on a computer useable storage medium for execution by a computer.As an example, an embodiment of a computer program product includes acomputer useable storage medium to store a computer readable program.

The computer-useable or computer-readable storage medium can be anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system (or apparatus or device). Examples ofnon-transitory computer-useable and computer-readable storage mediainclude a semiconductor or solid-state memory, magnetic tape, aremovable computer diskette, a random-access memory (RAM), a read-onlymemory (ROM), a rigid magnetic disk, and an optical disk. Currentexamples of optical disks include a compact disk with read only memory(CD-ROM), a compact disk with read/write (CD-R/W), and a digital videodisk (DVD).

Alternatively, embodiments of the invention may be implemented entirelyin hardware or in an implementation containing both hardware andsoftware elements. In embodiments which use software, the software mayinclude but is not limited to firmware, resident software, microcode,etc.

Although specific embodiments of the invention have been described andillustrated, the invention is not to be limited to the specific forms orarrangements of parts so described and illustrated. The scope of theinvention is to be defined by the claims appended hereto and theirequivalents.

What is claimed is:
 1. A method of managing block acknowledgementoperations in a multi-link communications system, the method comprising:transmitting a request for block acknowledgement response from a firstmulti-link device to a second multi-link device, wherein the request iseither in quality of service (QoS) data frames of aggregated-mediaaccess control (MAC) protocol data unit (A-MPDU) or a blockacknowledgement request; and receiving a block acknowledgment from thesecond multi-link device by the first multi-link device.
 2. The methodof claim 1, wherein the request for block acknowledgement responseincludes sequence number bits in a starting sequence number field andadditional sequence number bits in another field of the request.
 3. Themethod of claim 2, wherein the additional sequence number bits are in afragment number field of a block ack start sequence control field in therequest.
 4. The method of claim 1, wherein the block acknowledgementrequest includes an indication whether a recipient of the blockacknowledgement request needs to update at least one of WinStartB andWinStartR value when a block acknowledgement agreement with therecipient is not a protected block agreement.
 5. The method of claim 1,wherein one block acknowledgement bitmap field in the blockacknowledgement is used to acknowledge QoS data frames of a trafficidentification (TID) from an A-MPDU source.
 6. The method of claim 1,wherein a plurality of bits in a fragment number field of a startingsequence number control field of a block acknowledgement informationfield in the block acknowledgement indicates that a block acknowledgmentbitmap field is more than 256 bits and also indicates size of the blockacknowledgment bitmap field.
 7. The method of claim 6, wherein B3 offragment number field being equal to 1, B0 of fragment number fieldbeing equal to 0 and various values of B2 and B1 of fragment numberfield indicate the block acknowledgment bitmap field with bit length of512 or
 1024. 8. The method of claim 1, wherein the block acknowledgementis carried in greater than 20 MHz Extremely High Throughput (EHT)physical protocol data unit (PPDU).
 9. The method of claim 1, wherein ablock acknowledgement bitmap length of the block acknowledgement isbased on a difference of sequence numbers of acknowledged frames insteadof a negotiated block acknowledgement buffer size.
 10. The method ofclaim 1, wherein the block acknowledgement request is carried in anA-MPDU to announce a starting sequence number of a solicited blockacknowledgement.
 11. A multi-link communications system comprising: afirst multi-link device; and a second multi-link device, wherein thefirst multi-link device is configured to transmit a request for blockacknowledgment response to the second multi-link device, wherein therequest is either in quality of service (QoS) data frames ofaggregated-media access control (MAC) protocol data unit (A-MPDU) or ablock acknowledgement request, and wherein the second multi-link deviceis configured to transmit a block acknowledgment to the secondmulti-link device.
 12. The multi-link communications system of claim 11,wherein the request for block acknowledgement response includes sequencenumber bits in a starting sequence number field and additional sequencenumber bits in another field of the request.
 13. The multi-linkcommunications system of claim 12, wherein the additional sequencenumber bits are in a fragment number field of a block ack start sequencecontrol field in the request.
 14. The multi-link communications systemof claim 11, wherein the request includes an indication whether arecipient of the request needs to update at least one of WinStartB andWinStartR value when a block acknowledgement agreement with therecipient is not a protected block agreement.
 15. The multi-linkcommunications system of claim 10, wherein one block acknowledgementbitmap field in the block acknowledgement is used to acknowledge QoSdata frames of a traffic identification (TID) from an A-MPDU source. 16.The multi-link communications system of claim 10, wherein a plurality ofbits in a fragment number field of a starting sequence number controlfield of a block acknowledgement information field in the blockacknowledgement indicates that a block acknowledgment bitmap field ismore than 256 bits and also indicates size of the block acknowledgmentbitmap field.
 17. The multi-link communications system of claim 16,wherein B3 of fragment number field being equal to 1, B0 of fragmentnumber field being equal to 0 and various values of B2 and B1 offragment number field indicate the block acknowledgment bitmap fieldwith bit length of 512 or
 1024. 18. The multi-link communications systemof claim 10, wherein a block acknowledgement bitmap length of the blockacknowledgement is based on a difference of sequence numbers ofacknowledged frames instead of a negotiated block acknowledgement buffersize.
 19. A multi-link device of a multi-link communications system, themulti-link device comprising: a processor configured to: transmit arequest for block acknowledgement response to a second multi-link deviceof the multi-link communications system, wherein the request is eitherin quality of service (QoS) data frames of aggregated-media accesscontrol (MAC) protocol data unit (A-MPDU) or a block acknowledgementrequest; and receive a block acknowledgment from the second multi-linkdevice.
 20. The multi-link device of claim 19, wherein the request forblock acknowledgement response includes sequence number bits in astarting sequence number field and additional sequence number bits inanother field of the request.